Energy renovation inside and outside the building

To find out more about energy renovation and optimisation of existing buildings, read on and find out what a pair of experts have to say. First a man with hands-on experience of energy optimisation, Dainius Matusevicius, Project Manager Energy for Grundfos Corporate Service.

Most efficient approachIn his experience, the most efficient way to upgrade the building and reduce energy consumption is to start inside the building: “Look at the engineered systems of the building. That is water supply, heating and HVAC systems, maybe also wastewater. These are the areas with the quickest payback, best energy efficiency and the most immediate benefits.”

Low hanging fruitIn other words, this is where the low hanging fruit can be found. According to Mr. Matusevicius, this might not be provide the greatest energy-savings in absolute terms, but it will deliver fast results. Replacing pumps, for example, can typically cut energy consumption by 40% and pay for itself in 2 years. And then, the pump will continue to work for another 10-15 years.

Know what you have!According to Mr. Matusevicius, building owners often overlook a very important step when embarking on an energy optimisation. That is: “You need to know what you have before starting an energy optimisation. If you are not aware of how much energy your building is using right now then you will not know what you are aiming for.” This should be the first step in any energy renovation. Then the owner can begin to look at the cost of investment needed to achieve a particular goal.

"Look at the engineered systems of the building. That is water supply, heating and HVAC systems, maybe also wastewater. These are the areas with the quickest payback, best energy efficiency and the most immediate benefits."

Energy checkMr. Matusevicius goes on to explain how he would go about an energy optimisation. Step one would be an energy check, where the technician goes onsite and lists all pumps, age, running hours, etc. Based on this, potential energy savings can be calculated.

For larger optimisation projects, experts can also carry out a pump audit: “Here we go onsite and install instruments and collect data. The result is hard facts that tell us exactly how the system operates and the precise savings potential.”

Building envelopeMr. Matusevicius recognises that improving the building envelope with e.g. new insulation, windows, roof etc. will certainly provide energy savings. But it will also involve higher levels of investment. As he puts it: “Altering the building envelope to lessen heat loss, for example, can often require an investment 10-15 times greater than replacing a pump installation – and will never provide a payback time of 2 years.”

You need to know what you have before starting an energy optimisation. If you are not aware of how much energy your building is using right now then you will not know what you are aiming for.

Maximum energy renovation
On the other hand, if the owner really wants to maximize energy savings, what then? Investing in the inside and outside of the building at the same time makes a lot of sense: “If someone insulates the building, or puts in new windows, the heat loss from that building is reduced. Then if the heating and air conditioning systems are designed for a poor building envelope, the systems will now be far too oversized. There could even be side-effects, where very good insulation makes the building air-tight.”

In such cases, looking at the HVAC systems inside the building at the same time as altering the building envelop is a smart move.

Improved comfort
By improving the energy efficiency of the building, by putting in extra insulation and improving the building envelope, the owner can reduce energy loss, meaning less energy is required to maintain the same level of comfort inside the building – or even to increase comfort while using less energy.

Background
Mr. Matusevicius has been with Grundfos for more then 10 years, both as sales manager for East European countries and as an application manager in the Central and Eastern European sales region. His experience is currently being utilised in a corporate service function throughout Europe and beyond.

Interview: The building envelope

PHOTO: Professor Carsten Rode, Head of Section for Building Physics and Services, Department of Civil Engineering, Technical University of Denmark

Building physics and envelopes

Professor Carsten Rode is Head of Section for Building Physics and Services in the Department of Civil Engineering at the Technical University of Denmark. He is a leading expert on building physics and building envelopes.

The building envelopeProfessor Rode would begin an energy renovation with the outside of the building, in particular the building envelope. He says: “If you are talking about renovation, then do what you can in terms of ventilation and changing windows.” And, of course, insulation, though this may present some other challenges.

InsulationAccording to Professor Rode, while insulation is important, it can sometimes present challenges: “Insulation can be a challenge because it changes the building envelope. Also, indoor insulation is not so attractive for various reasons – both building physical and because it takes some space from your rooms. There are, though, some new insulation types which save space, but these are probably still too expensive in practical terms.”

It is not just about optimising the individual building, but really seeing it in the context of its environment.

Professor Carsten Rode, Head of Section for Building Physics and Services, Department of Civil Engineering, Technical University of Denmark

According to Professor Rode, from a technical viewpoint outside insulation is best, but it also changes the building and its appearance. Additional insulation may in some locations, such as roof spaces, be easier to install.

Fighting internal gains
Professor Rode also brings up the issue of internal heat gains. This is the heat emitted by occupants, machinery, building use etc. In a building with lots of glazing, internal heat gains may be even higher, as heat from the sun in the form of solar gains can also be an issue. Heat gains are a problem for the indoor thermal environment and something that energy refurbishments can address.

According to Professor Rode: ”This is of course one of the reasons why even in a country like Denmark, lots of commercial buildings are installing cooling systems due to overheating. In a temperate climate it should be possible to avoid this by employing passive solutions”. Though this will also depend on the use of the building.

In the future, we will see more and more that buildings are coupled to the grid in various ways, with exchange of different energy services and data for management and control.

Professor Carsten Rode, Head of Section for Building Physics and Services, Department of Civil Engineering, Technical University of Denmark

Passive solutions
Professor Rode talks about the passive solutions that could be incorporated in an energy refurbishment: “There are techniques such as passive ventilation, solar shading and automatic ventilation systems. Fitting solar shading, for example, into an existing building is possible but should be done in a way that is both functional and aesthetically pleasing”.

As is always the case, for energy renovations it is a question of what makes practical and economic sense. Professor Rode is also a member of the Active House Alliance, a non-profit network working to promote knowledge sharing and cooperation between interested parties involved in building projects, product development, research and performance.

Existing buildings will never be zero energy buildings
When asked about so-called zero-energy buildings, the professor tells us that existing buildings can almost never become zero-energy, regardless of the extent of energy renovation. Overall they will not achieve a positive energy balance. Or, at least, not alone.

Be smart with a holistic approach
While it is important to think about maximizing the energy efficiency of individual buildings, according to Professor Rode a more holistic approach is required, one that combines buildings with solutions for the community: “In the future, we will see more and more that buildings are coupled to the grid in various ways, with exchange of different energy services and data for management and control. Your building will at times produce energy that you do not need, which another building in your community could use, because it has a different purpose and user pattern. And vice versa.”

The buildings in a community could become zero energy consuming by exchanging energy services. “It is not just about optimising the individual building, but really seeing it in the context of its environment”, Professor Rode explains.

Coupled to the grid on a community scale
This would require all buildings to be grid connected, so the energy-saving factors in individual buildings could be combined in the local community. He finishes: “That is what we are looking at right now. There is a lot of research activity on zero carbon communities and smart cities. We need to find still more advanced combined solutions in the years to come.”

The big picture

Inside and outside the building: From A-Z and top to bottom

Looking at the latest research and information, what could a full energy renovation of a commercial building involve? Here is a very quick overview of additional measures:

• Replacing pumps and other energy consuming products in HVAC systems can provide significant, immediate and cost-effective savings for any building renovation.

• Mixed mode ventilation: Existing buildings might not be able to fully utilise passive ventilation. A mixed mode cooling and ventilation system could be installed, which combines an automated natural ventilation system and an automated mechanical cooling system for when temperatures are too high for the passive system to cope with.

• Lighting: Install LED lighting, daylight and occupancy controls and optimise the use of daylight by adding light shelves to even out the diffusion of daylight in the building.

• Solar gain: Reduce solar gain by installing external louvres.

• Passive solar heating: Solar heating can also be stored for use when the building cools down.

• Greening the building: Vegetating the building surfaces such as roofs help cool the building and increase thermal insulation.